Did a bit of Lich grinding over the last few days (12 so far, 3 for new weps), valence fusion feels like it could be more generous with its upgrades.
RNG is RNG, 8 / 9 of the duplicates I got are of a lower roll than what I have, and as you fuse to a higher damage %, the probability of getting a higher roll is even less. Going by the current 10% increase it takes 10 Liches (maximum) to cap out the weapon bonus, given an average of 2-3 hours per lich, not including requiem mod farming, takes up to 7 Liches or ~20 hours (on average) of dedicated farming for a maxed weapon, which feels a little too much. Considering we have 16 Kuva weapons, that's 320 hours of just Liches alone.
Would suggest bumping it up to at least +20% per transfer, which is about 5 fusions max to get to 60% bonus, still takes ~160 hours minimum for everything though (which tbh, is probably already way more than it should be), with exceptions towards extremely lucky rolls.